The EML4-ALK fusion gene is responsible for approximately 3-5% of Non Small Cell Lung Cancer. The vast majority of cases are adenocarcinomas. Rearrangements of the gene encoding ALK have been linked to abnormal cell proliferation and NSCLC. The most common ALK rearrangement in NSCLC is EML4-ALK, which arises from fusion between the EML4 gene and the ALK gene on chromosome 2p23. Patients with ALK rearrangements do not respond to the EGFR-specific TKI therapy. ALK gene rearrangements have implications in both Hematological and Solid Malignancies.